function dispBlock(img, pos, blknum1, blknum2)
p1 = img(pos{blknum1}(1):pos{blknum1}(2),pos{blknum1}(3):pos{blknum1}(4),:);
p2 = img(pos{blknum2}(1):pos{blknum2}(2),pos{blknum2}(3):pos{blknum2}(4),:);
subplot(1,2,1);
imshow(p1);
hold on;
subplot(1,2,2);
imshow(p2);
hold off;
end

